Chapter 2: Statistical Variation Flashcards
N =?
total number of subjects or scores…
n=subsample of the sample..
N= the total sample
X or Y = ??
variables that are measured…
Xi=??
i can vary from 1-N……the iTH score..
Summation?
N
Σχi
i= 1
N= last score in summation.. x= variable... i= first score in the summation... summation= sum of data..
Scales of measurement ?
determine types of tests used to analyze
different scales have different properties….
Properties of Measurement Scales?
Property of identity..
equal unit size…
absolute zero
magnitude/ordinality
Property of Identity ..
each value represents a descriptive category..
ex: drink brand, religious affiliation…
Property of Magnitude/ ordinality..
assigned values reflect greater than and less than…
grading scheme = ex !
Property of Equal unit size?..
difference between numbers are the same…..
ex: 120-130…and 180-190
Property of Absolute zero?
zero represents nothing of the variable…
…….# of cars in a parking lot? zero? zero= no cars….ex
Types of scales?? 4
Nominal, ordinal, interval and ratio scales…
Nominal Scale
property involved?
lowest scale of measurement
deals with qualitative data not quantitative data..
property = identity
no value difference between variables….
cannot add or avg..
good for comparisons ….how many of something…
Ordinal Scale?
Property?
deals with data that can be ordered or ranked.... ex: olympic race..... 1st , 2nd , 3rd there are no in between numbers.. property: identity, magnitude.. A>B B>C ... A=F
Interval Scale?
property?
distance between ranked differences are =
Property: identity, magnitude, and interval properties..
zero is arbitrary..
can: a-b=c ..c-d…a-b>c-d..
cant do ratios no mult or divison…
Ratio Scale?
property?
Interval with true zero point….
score of zero = no amount of variable!
Property: identity, magnitude, equal interval and absolute zero!
can do all math operations…
Discrete Variables?
scales?
no possible values between adjacent units…
whole numbers units or categories…
cant have 3 and a half cats!
nominal and ordinal!
Continuous Variables..
scales?
can take infinite variable values in between units…
ex: drug dosage….10mg..10.1 mg…etc..
interval or ratio!
Real Limit?
values are set at 1/2 of the scale…..
score of 72 really means 72 +/- 0.5
URL: 72.5
LRL: 71.5
Upward Rounding bias?
we round up more times than we round down…
Solution to upward rounding bias!?
remainder is >5, round up
Remainder is <5, round down
Remainder is = 5 and last digit even, round down
Remainder is = 5 and last digit is odd, round up
ex: 26.6= 27
25.5 = 26…
